import java.util.Scanner;

public class One {
    public static void main(String[] args) {
        Scanner in=new Scanner(System.in);
        long x=in.nextLong();
        long a=(long)Math.sqrt(x);
        long x1=a*a,x2=(a+1)*(a+1);
        if(x-x1<x2-x)
            System.out.println(x1);
        else
            System.out.println(x2);
    }
}
